South Africa's former President Nelson Mandela has undergone more medical tests in a military hospital as the public and journalists outside asked: What, if anything, is wrong with the health of the 94-year-old anti-apartheid icon?

Government officials in charge of releasing information about Mandela have repeatedly declined to provide specifics about Mandela's now three-day hospitalisation, calling on citizens to respect the beloved politician's privacy.

Yet Mandela represents something more than a man to many in this nation of 50 million people and to the world at large, and the longer he remains in hospital care, the louder the demand for the private details about his health will grow.

"He symbolises what our country can achieve with a statesman of his stature. He's our inspiration and personifies our aspirations," an editorial in Monday's edition of the Sowetan newspaper reads.

"And that's why we dread his hospital visits, routine or not. That's why even now when we are told not to panic, we do."

Mandela is revered for being a leader of the struggle against racist white rule in South Africa and for preaching reconciliation once he emerged from prison in 1990 after 27 years behind bars.

He won South Africa's first truly democratic elections in 1994, serving one five-year term.

The Nobel laureate later retired from public life to live in his remote village of Qunu, in the Eastern Cape, and last made a public appearance when his country hosted football's 2010 World Cup.

On Saturday, President Jacob Zuma's office announced Mandela had been admitted to a Pretoria hospital for medical tests and for care that was "consistent for his age."

Zuma visited Mandela on Sunday and found the former leader to be "comfortable and in good care," presidential spokesman Mac Maharaj said in a statement.

Such is the level of confidentiality surrounding Mandela's hospitalisation that it wasn't until Monday that the public received government confirmation that he was being treated at 1 Military Hospital in Pretoria, the capital.

That word came from Defence Minister Nosiviwe Mapisa-Nqakula, who visited the aging leader there. Speaking to journalists afterward, Mapisa-Nqakula said Mandela was "undergoing a series of tests to determine what is going on in his body." She said Mandela's release date would be determined by the result of those tests.

"He's doing very, very well," Mapisa-Nqakula said. "And it is important to keep him in our prayers and also to be as calm as possible and not cause a state of panic because I think that is not what all of us need."

The presidency later issued a statement saying Mandela "had a good night's rest" and would have more tests done.

"He is in good hands," Maharaj said in the statement.

Mandela has had a series of health problems in his life. He contracted tuberculosis during his years in prison and had surgery for an enlarged prostate gland in 1985.

In February, Mandela spent a night in a hospital for a minor diagnostic surgery to determine the cause of an abdominal complaint.

In January 2011, Mandela was admitted to a Johannesburg hospital for what officials initially described as tests but what turned out to be an acute respiratory infection.

The chaos that followed Mandela's stay at that public hospital, with journalists and the curious surrounding it and entering wards, saw the South African military take over his care and the government control the information about his health. That has brought many to complain about the lack of concrete details released about Mandela's condition in the last three days.

Much of that frustration comes from people's feelings that Mandela is more than a man or a national politician, said Frans Cronje, the deputy chief executive of the South African Institute of Race Relations.

"Mandela is what people like to remember about South Africa's transition. It's what they like to remember about the country," Cronje said.

"As we get confronted with more evidence of large-scale corruption ... I think there are people who look to Mandela as an example and say, 'We were better than this once.'"

Mandela, however, disengaged himself with the country's politics fairly successfully over the last decade. But he remains almost a talisman for racial reconciliation, with one artist in India feeling so strongly about Mandela's health that he sculpted his face out of sand on a beach on Sunday in the town of Puri.

Near the face, he wrote out in sand: "Get well soon."

That's a wish that's been repeatedly broadcast across television and radio stations in South Africa, printed in newspaper headlines and whispered as prayers in recent days for the increasingly frail icon.